Exam-like questions

From last years resit:
The following knowledge may be used for recommending garden trees:
``You should get a tree of suitable size for your garden, and one that is suitable for your family. If your garden is small then small trees are of suitable size. If you have children then non-poisonous trees are appropriate. Laburnum, Yew and Japanese Maple are all small, while Spruce and Sycamore are large. Laburnum and Yew are poisonous.''
Represent the above knowledge as a set of production rules (and possibly initial facts). Briefly describe how the rules might be used to check on the suitability of a proposed garden tree (say, Japanese Maple) using backward chaining.
An exam-like question:
Given the following set of rules:

1. What new facts would be deduced using forward chaining given the following initial facts:

   (month february)
   (year 1993)

   [ 8 marks]

2. Briefly describe how the following could be proved/disproved using backward chaining: (bad-mood alison) [8 marks]

3. Why might you choose to use backward chaining rather than forward chaining in an expert system [9 marks].